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Chemistry: Post your doubts here!

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The shell of a chicken’s egg makes up 5% of the mass of an average egg. An average egg has a


mass of 50 g.

Assume the egg shell is pure calcium carbonate.

How many complete chicken’s egg shells would be needed to neutralise 50 cm3 of 2.0 mol dm–3

ethanoic acid?
So we are neutralising ethanoic acid using calcium carbonate:
2CH3COOH + CaCO3 --> (CH3COO)2Ca + H2O + CO2

Moles of ethanoic acid = 50/1000 * 2 = 0.1mol
Moles of CaCO3 required = 0.1/2 = 0.05mol
Mass of this CaCO3 = 0.05*Mr(CaCO3)= 5g

So we want 5g of eggshell.
Mass of average eggshell = 50g*5% = 2.5g
Number of eggshell required = 5/2.5 = 2 eggshells

Hope that was helpful :)
 
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I don't understand the concept behind s,p,d sub-shells and orbitals and also the Aufbau principle. Can any please explain the basics?
 
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I did and I still don't understand it properly. :(
Well I'll be straight with you. That website, chemguide, is one of the best websites I've seen for chemistry. In fact, you can rely just on this one website for all your a level needs. However, it is true that students have different learning types. Some are visual learners, others need ppl to explain orally, etc.
I think it's difficult to explain whole concepts by typing here. You should go talk to your teacher. Go sit down with him and let him explain everything till you get it. Or perhaps a knowledgeable classmate. Or a senior student. Hope you learn it well :)

PS. If there is a specific paragraph from the link you didn't understand, just quote it and explain what you don't get, I'll try my best to elucidate.
 
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Metanoia or anyone else, help me remembering As level inorganic stuffs, that are chapters, Periodicity, Group II and VII and sulfur and nitrogen...
Just temme what is importantand what is the trick to remember those stuffs. Thanks.
 
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Metanoia or anyone else, help me remembering As level inorganic stuffs, that are chapters, Periodicity, Group II and VII and sulfur and nitrogen...
Just temme what is importantand what is the trick to remember those stuffs. Thanks.

Its not easy to say what is important or not.

Its best for you to look through the objectives listed for the respective chapters and make sure you understand the requirements.
http://www.cie.org.uk/images/128593-2015-syllabus.pdf

If any objective seems unfamiliar, its an indication you need to revise that particular concept.
 
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